1. Field of the Invention
The present invention relates to a solid electrolytic capacitor formed by mounting a capacitor element on an insulating substrate.
2. Description of Related Art
As a conventional solid electrolytic capacitor, known is a capacitor having a structure shown in FIG. 12. This solid electrolytic capacitor includes a capacitor element 91, an anode terminal 93, a cathode terminal 94, and an enclosure resin 92. An anode lead member 912 which is a part of the capacitor element 91 is electrically connected to the anode terminal 93 by resistance welding. A cathode section (not shown) of the capacitor element 91 is electrically connected to the cathode terminal 94 by an electrically-conductive adhesive (not shown). The anode terminal 93 and the cathode terminal 94 are drawn out from the enclosure resin 92, and are bent along a side surface and a lower surface of the solid electrolytic capacitor. Thus, an anode terminal lower surface part 93b and a cathode terminal lower surface part 94b form lower surface electrodes of the solid electrolytic capacitor.
As another conventional solid electrolytic capacitor, known is a capacitor having a structure shown in FIG. 13. This solid electrolytic capacitor includes the capacitor element 91, a wiring member 95 (e.g., a printed board) and the enclosure resin 92. The wiring member 95 includes an insulating base 950. The anode terminal 93 comprises a first anode terminal portion 931a formed on an upper surface 951 of the insulating base 950, a second anode terminal portion 932a formed on a lower surface 952 of the insulating base 950, and an anode via 933a opening in the insulating base 950 to electrically connect the first anode terminal portion 931a and the second anode terminal portion 932a to each other. The cathode terminal 94 comprises a first cathode terminal portion 941a formed on the upper surface 951 of the insulating base 950, a second cathode terminal portion 942a formed on the lower surface 952 of the insulating base 950, and a cathode via 943a opening in the insulating base 950 to electrically connect the first cathode terminal portion 941a and the second cathode terminal portion 942a to each other.
In the solid electrolytic capacitor described above, to the first anode terminal portion 931a, electrically connected is the anode lead member 912 of the capacitor element 91 through a pad member 98, while, to the first cathode terminal portion 941a, electrically connected is the cathode section (not shown) of the capacitor element 91 by the electrically-conductive adhesive (not shown). The second anode terminal portion 932a and the second cathode terminal portion 942a form the lower surface electrodes of the solid electrolytic capacitor.
As a further conventional solid electrolytic capacitor, known is a capacitor having a structure shown in FIG. 14. This solid electrolytic capacitor includes the capacitor element 91, the wiring member 95 (e.g., a printed board) and the enclosure resin 92. The wiring member 95 includes the insulating base 950. The anode terminal 93 comprises a first anode terminal portion 931b formed on the upper surface 951 of the insulating base 950, a second anode terminal portion 932b formed on the lower surface 952 of the insulating base 950, and an anode via 933b opening in the insulating base 950 to electrically connect the first anode terminal portion 931b and the second anode terminal portion 932b to each other. The cathode terminal 94 comprises a second cathode terminal portion 942b formed on the lower surface 952 of the insulating base 950, and a cathode via 943b opening in the insulating base 950 to be electrically connected to the second cathode terminal portion 942b. 
In the solid electrolytic capacitor described above, the first anode terminal portion 931b is electrically connected to the anode lead member 912 of the capacitor element 91, while the cathode via 943b is electrically connected to the cathode section (not shown) of the capacitor element 91 by the electrically-conductive adhesive (not shown). The second anode terminal portion 932b and the second cathode terminal portion 942b form the lower surface electrodes of the solid electrolytic capacitor.
However, in the manufacturing process of the conventional solid electrolytic capacitor shown in FIG. 12, required is a complicated work to bend the anode terminal 93 and the cathode terminal 94. Also, since the enclosure resin 92 of appropriate thickness needs to be intervened between the lower surface of the capacitor element 91 and the anode terminal lower surface part 93b, and between the lower surface of the capacitor element 91 and the cathode terminal lower surface part 94b, there has been a problem of lower occupancy of the capacitor element 91 in the solid electrolytic capacitor, or, a problem of greater equivalent series resistance (ESR) and equivalent series inductance (ESL) due to an increase in length of the anode terminal 93 and the cathode terminal 94.
In the conventional solid electrolytic capacitor shown in FIG. 13, the anode lead member 912 of the capacitor element 91 and the anode terminal 93 are connected to each other by the pad member 98 which is a different member from the wiring member 95. Therefore, in a manufacturing process of the capacitor, required is a process to fix the pad member 98 to the anode terminal 93. Also, the ESR or ESL might increase significantly due to poor connection or the like generated between the pad member 98 and the anode terminal 93.
In the conventional solid electrolytic capacitor shown in FIG. 14, the first anode terminal portion 931b and the anode via 933b are produced by electrolytic plating. A thickness D1 of a plating layer forming the anode terminal 93 (a distance between the anode lead member 912 and the second anode terminal portion 932b) is substantially different from a thickness D2 of a plating layer forming the cathode terminal (a thickness of the wiring member 95). Therefore, in the case where the plating formations of the anode terminal portion and the cathode terminal portion are performed simultaneously, it is considerably difficult to control the plating layer thickness D1 and the plating layer thickness D2 to be desired thicknesses, and therefore, there has been a problem of significantly poor yield ratio. Moreover, in the case where the formation of the plating layer having the thickness D1 to form the anode terminal portion and the formation of the plating layer having the thickness D2 to form the cathode terminal portion are performed in separate processes, the number of the plating processes is doubled. Therefore, there has been a problem of cost increase such as working hour, plating liquid replacement or the like.
In addition, since the thickness D1 of the plating layer is several hundred μm, there has also been a problem of longer time for electrolytic plating and greater man-hour which could lead to cost increase.